Response: The increased social and economic burdens for osteoporotic-related fractures worldwide make its prevention a major public health goal.

Calcium and vitamin D supplements have long been considered a basic intervention for the treatment and prevention of osteoporosis. Survey analysis showed that 30–50% of older people take calcium or vitamin D supplements in some developed countries. Many previously published meta-analyses, from the high-ranking medical journals, concluded that calcium and vitamin D supplements reduce the incidence of fracture in older adults. And many guidelines regarding osteoporosis recommend calcium and vitamin D supplements for older people. The final aim for these supplements is to prevent the incidence of osteoporotic-related fracture in osteoporosis management.

David Jolliffe, PhDCentre for Primary Care and Public Health
Blizard Institute
Barts and the London School of Medicine and Dentistry
London

MedicalResearch.com: What is the background for this study?

Response: Asthma affects more than 300 million people worldwide and is estimated to cause almost 400,000 deaths annually. Asthma deaths arise primarily during episodes of acute worsening of symptoms, known as attacks or ‘exacerbations’, which are commonly triggered by viral upper respiratory infections. Vitamin D is thought to protect against such attacks by boosting immune responses to respiratory viruses and dampening down harmful airway inflammation.

Several clinical trials have tested whether vitamin D supplementation might protect against asthma attacks, but individually their results are inconclusive. In the current study, we pooled raw data from 955 asthma patients who took part in 7 separate trials, which allowed us to answer two questions:

1, Does vitamin D protects against asthma attacks overall, when data from all trials are pooled?

2, Do people who have lower vitamin D levels to start with particularly benefit from supplementation?

MedicalResearch.com: What is the background for this study? What are the main findings?

Response: Some previous epidemiological studies have suggested that low vitamin D levels are associated with increased rates of asthma, atopic dermatitis—an itchy inflammation of the skin—and elevated levels of IgE, an immune molecule linked to atopic disease (allergies). In our study, we looked at genetic and health data on more than 100,000 individuals from previous large studies to determine whether genetic alterations that are associated with vitamin D levels predispose people to the aforementioned conditions.

We found no statistically significant difference between rates of asthma (including childhood-onset asthma), atopic dermatitis, or IgE levels in people with and without any of the four genetic changes associated with lower levels of 25-hydroxyvitamin D, the form of vitamin D routinely measured in the blood.

MedicalResearch.com Interview with:Robert Scragg, MBBS, PhD
School of Population Health
The University of Auckland
Auckland New Zealand

MedicalResearch.com: What is the background for this study? What are the main findings?

Response: Interest in a possible role for vitamin D deficiency as a risk factor for cardiovascular disease was stimulated by studies showing a seasonal variation in cardiovascular disease, which is much higher in winter, when body levels of vitamin D are low, than in summer.

Main findings are that bolus monthly doses of vitamin D supplementation do not prevent against cardiovascular disease, even in people with low levels of vitamin D.

However, the scientific fields consider randomized clinical trials (RCT) as a gold standard for testing new interventions for prevention and treatment of disease. In the only RCT of cancer and vitamin D to date with cancer as a primary outcome, the Women’s Health Initiative, postmenopausal women randomly assigned to vitamin D3400 IU/day and calcium 1000 mg/day showed no difference from those assigned to placebo in colorectal cancer incidence. One criticism of that study was that the vitamin D intervention was low, only 400 international units (IU) per day.

In our study we found that, in healthy women ages 55 and older with a mean baseline serum 25(OH)D of 33 ng/mL, supplementation with 2000 IU/day of vitamin D3and 1500 mg/day of calcium for four years, compared with placebo, decreased all-type cancer incidence by about 30%, but this did not reach statistical significance. (p value =0.057 and for statistical significance, the p value would need to be less than 0.05.)

In a secondary analysis, we re-analyzed the data excluding cancers that developed during the first year of study and were likely present but not diagnosed upon study enrollment. The findings here were that vitamin D and calcium did significantly decrease cancer risk by about 35%.

In another secondary analyses, we combined all of the serum 25(OH)D values to determine if higher levels were associated with lower cancer incidence. Here, higher serum 25(OH)D was significantly associated with lower cancer incidence. Persons with serum 25(OH)D of 55 ng/mL had a 35% lower risk of cancer than persons with serum 25(OH)D of 30 ng/mL. This is especially interesting since current recommendations for sufficient serum 25(OH)D levels are 20 ng/mL (the National Academy of Medicine) and 30 ng/mL (the Endocrine Society).

Note that serum 25(OH)D is a better predictor of cancer development than assigning persons to supplement groups. Serum 25(OH)D takes into account poor compliance of the active supplement group with taking supplements, personal use of supplements by the placebo group, dietary vitamin D intake, sunlight exposure, and the variation among persons in absorption and metabolism of the vitamin D supplement.

MedicalResearch.com: What is the background for this study? What are the main findings?

Response: Previous research has found that daily administration of vitamin D is important for maintaining bone homeostasis. There has been an increased interest among the orthopaedic community regarding vitamin D supplementation and patient outcomes following fractures. Using data from the FAITH trial (NCT01908751), a multicenter randomized controlled trial that compared cancellous screws versus sliding hip screws in patients over the age of 50 with femoral neck fractures, we:

1) determined the proportion of patients consistently taking vitamin D following hip fracture surgery and
2) determined if supplementation was associated with improved health related quality of life and reduced re-operation.

Patients enrolled in the FAITH trial were recruited from 81 clinical sites in 8 countries over a 6-year span. We asked a subset of them about vitamin D supplementation and categorized them as consistent users, inconsistent users, or non-users.

The final analysis included 573 patients and we found that a surprisingly low proportion of elderly hip fracture patients are consistently taking vitamin D (18.7% of patients reported never taking vitamin D, 35.6% reported inconsistent use, and 45.7% reported consistent use). We also found that vitamin D was associated with a statistically (p=0.033), but not clinically, significant improvement in health-related quality of life following a hip fracture. Lastly, supplementation was discovered to not be associated with reduced re-operation (p=0.386).

Response: Fetal bone mineralisation requires an adequate transfer of calcium to the fetus by the end of the pregnancy. Considering that vitamin D is required to maintain normal blood concentrations of calcium, adequate 25-hydroxyvitamin D (25[OH]D) concentrations in pregnant women seem to be crucial for bone development of the offspring. Maternal vitamin D deficiency during pregnancy has been associated with abnormal early skeletal growth in offspring and might be a risk factor for decreased bone mass in later life.Several studies have linked vitamin D deficiency in fetal life to congenital rickets, craniotabes, wide skull sutures and osteomalacia. However, the evidence of long-lasting effects of maternal vitamin D deficiency during pregnancy on offspring’s skeletal development is scarce and inconsistent, and has led to contradictory recommendations on vitamin D supplementation during pregnancy.

MedicalResearch.com Interview with:
Dr. Adrian R MartineauB Med Sci DTM&H MRCP PhD
Clinical Professor of Respiratory Infection and Immunity
Centre for Primary Care and Public Health.
Blizard Institute, Barts and The London School of Medicine and Dentistry
Queen Mary, University of London

MedicalResearch.com: What is the background for this study?

Response: In addition to its well-known effects on bone, Vitamin D has also been shown to boost immune responses to viruses and bacteria that cause respiratory infections in lab experiments.

In order to see whether these effects translate into a health benefit, a total of 25 clinical trials of vitamin D supplementation to prevent various respiratory infections have been carried out in around 11,000 people living in 14 different countries over the last decade.

These trials have yielded conflicting results: in some, vitamin D reduced the risk of infections, but in others it did not.

The reason why vitamin D ‘worked’ in some trials, but not in others, has been the subject of much debate.

In order to answer this question, we assembled an international consortium of investigators and compiled the raw data from every trial into a single database containing information from 10,933 people in total. This allowed us to run sub-group analyses to determine whether particular groups of people benefit more from vitamin D supplementation than others.

MedicalResearch.com: What is the background for this study? What are the main findings?

Response: Formation of vitamin D in the skin with UVB light from the sun is a main source of vitamin D during summer months, but in the winter months the UVB light is too weak for vitamin D production. Headache prevalence has been suggested to be related to increasing latitude (less UVB light throughout the year) and possibly to be less prevalent during summer (more UVB light), which suggests a possible role for vitamin D exposure.

Some previous small studies have suggested that low serum vitamin D levels might be associated with more frequent headache or migraine. Our study included 2601 men from the Kuopio Ischaemic Heart Disease Risk Factor Study (KIHD) from eastern Finland, aged 42-60 years in 1984-1989, which makes it one of the largest studies so far regarding vitamin D and headache.

When we divided the study population into four groups based on their serum vitamin D levels, the group with the lowest levels had over a twofold risk of chronic headache in comparison to the group with the highest levels. Chronic headache was also more frequently reported by men who were examined outside the summer months of June through September.

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